Transmission shift forks have been common in transmissions and drive trains for some time. More recently, vehicles that can selectively be shifted between drive trains that engage two or four wheel drive are becoming increasingly popular. In many applications, the shift fork is the part of the drive assembly that is moved to engage or disengage a coupling between an input gear and an output gear. When the vehicle is in two wheel drive, the shift fork is positioned for disengagement and, conversely, when the shift fork is positioned for engagement the vehicle is in four wheel drive.
Known prior art shift forks of the type this invention concerns have suffered from two deficiencies. One deficiency has been wear on the fork or the surfaces OF THE dependent arm due to the continuous contact between the fork and the spinning coupling gear that is shifted by the fork. Another problem area has been wear and breakage of the fork's pilot pin which guides linear movement of the fork.
With respect to the first deficiency, there have been attempts to add wear pads to the surfaces of the fork that contact the gear flanges that define the outer edges of the race within which the fork rest when it engages the gear. However, this attempt has not been successful as did not alleviate the misalignment between the fork and the gear. This misalignment ultimately led to wear on the shaft or pin on which the fork rest for liner movement to effect the desired engagement. With respect to the defect in the shaft or pin, the inventors are not aware of any prior art attempt to address this problem.
The objects of the present invention are to provide a shift fork with improved pilot pin and contact wear surfaces.